The present invention relates to a hydraulic seed planter for a field planting system using large span and wheeled tower irrigation systems. More particularly, the invention provides apparatus which pre-germinates or primes seed, injects seed into a pressurized pipe transporting a stream of carrier water, distributes the seed and the carrier water to a plurality of manifolds each of which may be isolated from the supply pipe, and controls planting of the seeds from a manifold through a planting shoe which opens a furrow, places the seed in the furrow, and closes the furrow.
Planting of crop seed currently is limited primarily to tractor mounted or tractor drawn planters, which incorporate numerous types of seed metering systems. There are some crops which are seeded by airplane, but these are primarily limited to close seeded grain and cereal crops. Broadcast seeding through a ground applied fertilizer suspension has been attempted with varying degrees of success. Under development by the University of Georgia at Tifton, Ga. and Valmont Industries at Valley, Nebr. are seedagation systems in which seed is distributed through the main irrigation pipeline or an auxiliary pipeline and applied through large impact sprinklers. This may be considered a form of broadcast application with the seed remaining on the soil surface.
Various components of seed planting and irrigation systems have been described before. U.S. Pat. No. 4,300,461 issued to Hodge, et al. describes a seed planter which has a fluid injection soil opener. A seed applicator moves along the ground, and high pressure water discharged from a plurality of nozzles spaced along the applicator cuts narrow grooves in the ground. The seed is blown by air into the somewhat fluid soil. This device however, does not provide for covering the seed placed in the groove; instead, it relies on subsequent watering or rainfall to erode the grooves into themselves and effectively cover the seed.
It has further been known to use a liquid gel suspension to carry seeds from a storage container through a tube and into a furrow. U.S. Pat. No. 4,224,882 issued to Cruse describes an apparatus for sowing seeds in a liquid suspension. A peristaltic pump supplies the suspension to a furrow cut by a v-shaped coulter. The reference explains that the peristaltic pump does not damage seeds. However, it appears that the output performance of such a pump is influenced drastically by the pressure against which it pumps. For large span and wheeled tower planting systems, this type of pump and medium for carrying seed would not be practical Pressure differentials over these extended lengths would not permit uniform seed distribution along the planter.
U.S. Pat. No. 4,315,380 issued to Davidson describes a method of processing seeds or cereal to accelerate the natural germination of the seed. The seeds, steeped in water, are oxygenated in a temperature controlled container to pregerminate and/or store the seeds for planting.
As noted above, use of a liquid gel suspension has been used to meter seed into a furrow. Electronic metering devices described in U.S. Pat. No. 3,912,121 issued to Steffen and U.S. Pat. No. 4,333,096 issued to Jenkins et al., use electronic controls and microprocessors for tractor drawn seeding operations. These devices monitor and control the seeding rate. Jenkins '096 describes a dispensing mechanism which periodically dispenses seed through a chute into a furrow. A seed sensor provides an electronic signal to the monitor each time seed drops through the chute. A microprocessor counts the number of seeds planted in each row and alerts the operator if a stoppage occurs or if an excessive number of seed are being planted.
Steffen '121 describes an apparatus to control and maintain a preselected density of population of seeds delivered from a hopper by a seed dispensing mechanism to the furrows. The microprocessor controls the seed dispensing mechanism to increase, decrease, or hold constant the number of seeds dispensed, depending upon the number dispensed, the distance traveled, and the distance between rows.
U.S. Pat. No. 4,192,388 issued to Goebel describes disks to close ruts caused by the wheels of a center pivot or linear irrigation system running in wet soil. This reference describes the significant problem of operating heavy equipment through crop fields. Ruts are opened and crops are disturbed or damaged. Also the necessity to run a variety of tractor-drawn farm equipment through a field--i.e., tractors to plow and prepare fields, tractors to pull planters and plant seeds, tractors for cultivation and harvesting--all contribute to soil compaction, damage to crops and excess energy consumption. It is desirable to minimize the number of farm implements which must be used to farm land.
Mobile irrigation systems, which span across the crop field and which move through the field in either a linear or pivotal motion, offer the potential to reduce tractor-drawn operations by performing other functions in addition to irrigation. The framework of these large pipe span-and-tower systems provides a platform on which to install equipment to carry out additional farming operations. Precise chemical application for weed control from such an irrigation system, for example, can eliminate or reduce the need for the tractor-drawn plowing and cultivating operations. One such span-and-tower system is a multifunction irrigation system (MFIS) recently developed by The Texas A&M University System at the Agricultural Research & Extension Center in Lubbock, Tex. The A & M irrigation system provides uniform movement of the span-and-tower structure through a field and permits precise application of water and chemicals to the field and crops.
The A & M multifunction irrigation system incorporates two independent dynamic nozzle systems for precise water and chemical application. One set of nozzles is designated for water application through which chemicals may also be injected. The second nozzle system is exclusively for chemical injection. Many of the functions of the irrigation system include chemical application for the express purpose of reducing plant water stress by decreasing water loss from the soil and plants after irrigation. It further has the capability of precision application of other agricultural chemicals for the reduction of environmental stress on the plant, making it possible to reduce the need for tractors and other spraying equipment in the field after planting. Such a multifunction system provides the pipe span and wheeled tower structure to support a planting system of supply pipes, manifolds, drop tubes, and planting shoes as contemplated in the present invention.